RFR(XS) 8026939: assert(Reachblock != NULL) failed: Reachblock must be non-NULL

[Christian Thalinger]

On Oct 22, 2013, at 2:35 AM, Niclas Adlertz <niclas.adlertz at oracle.com> wrote:

> CTW and JPRT doesn't trigger this (that's why it was pushed unnoticed).
> However, I have tested 'java/lang/Character/CheckScript.java' with this fix and it now works.
> 
> (java/lang/Character/CheckScript.java was a failing test in nightlies)

Okay.  Looks good.

> 
> Kind Regards,
> Niclas Adlertz
> 
> On 2013-10-22 05:27, Christian Thalinger wrote:
>> What testing did you do?
>> 
>> On Oct 21, 2013, at 7:08 AM, Niclas Adlertz <niclas.adlertz at oracle.com> wrote:
>> 
>>> Hi all,
>>> 
>>> Now that more nodes can be rematerialized due to fix JDK-8022783, a rematerialized node can have a spilled live range as input even when rematerializing input for phi nodes (in the Phi Node Splitting pass).
>>> Prior to the JDK-8013830 and JDK-8005956 fixes, the Reachblock pointer could be wrong (hence the warning in JDK-8013830). Now, we pass in the correct block-reaches, i.e. the reaches for the 'pred' block.
>>> 
>>> Kind Regards,
>>> Niclas Adlertz
>>> 
>>> JBS:    https://bugs.openjdk.java.net/browse/JDK-8026939
>>> WEBREV: cr.openjdk.net is down so I'm pasting the diff here:
>>> 
>>> diff -r 52575a17a36c src/share/vm/opto/reg_split.cpp
>>> --- a/src/share/vm/opto/reg_split.cpp	Mon Oct 21 09:21:41 2013 +0400
>>> +++ b/src/share/vm/opto/reg_split.cpp	Mon Oct 21 15:34:42 2013 +0200
>>> @@ -365,7 +365,6 @@
>>>       }
>>>        if (lidx < _lrg_map.max_lrg_id() && lrgs(lidx).reg() >= LRG::SPILL_REG) {
>>> -        assert(Reachblock != NULL, "Reachblock must be non-NULL");
>>>         Node *rdef = Reachblock[lrg2reach[lidx]];
>>>         if (rdef) {
>>>           spill->set_req(i, rdef);
>>> @@ -476,7 +475,6 @@
>>>    uint                 bidx, pidx, slidx, insidx, inpidx, twoidx;
>>>   uint                 non_phi = 1, spill_cnt = 0;
>>> -  Node               **Reachblock;
>>>   Node                *n1, *n2, *n3;
>>>   Node_List           *defs,*phis;
>>>   bool                *UPblock;
>>> @@ -559,7 +557,7 @@
>>>      b  = _cfg.get_block(bidx);
>>>     // Reaches & UP arrays for this block
>>> -    Reachblock = Reaches[b->_pre_order];
>>> +    Node** Reachblock = Reaches[b->_pre_order];
>>>     UPblock    = UP[b->_pre_order];
>>>     // Reset counter of start of non-Phi nodes in block
>>>     non_phi = 1;
>>> @@ -1315,6 +1313,7 @@
>>>       pidx = pred->_pre_order;
>>>       // Grab reaching def
>>>       Node *def = Reaches[pidx][slidx];
>>> +      Node** Reachblock = Reaches[pidx];
>>>       assert( def, "must have reaching def" );
>>>       // If input up/down sense and reg-pressure DISagree
>>>       if (def->rematerialize()) {
>>> @@ -1327,8 +1326,7 @@
>>>                _lrg_map.find(pred->get_node(insert - 1)) >= lrgs_before_phi_split) {
>>>           insert--;
>>>         }
>>> -        // since the def cannot contain any live range input, we can pass in NULL as Reachlock parameter
>>> -        def = split_Rematerialize(def, pred, insert, maxlrg, splits, slidx, lrg2reach, NULL, false);
>>> +        def = split_Rematerialize(def, pred, insert, maxlrg, splits, slidx, lrg2reach, Reachblock, false);
>>>         if (!def) {
>>>           return 0;    // Bail out
>>>         }
>> 
>